This invention relates to extending nip presses, and to such a press useful in the papermaker's art, in which a newly-formed web of paper is carried on the surface of a felt, and is subjected to a dewatering or pressing force. In such extended nip presses, the felt and web carried on the felt are partially wrapped over a dewatering roll, and pressure is applied to the felt to force the felt against the roll. The dewatering or extraction roll may take the form of a grooved roll or perforated shell for recovery of water from the felt.
Magnetics has been suggested as the means for generating a pressing force in the nip of an extended nip press, by pressing a shoe against an impervious belt running against the felt, as shown in the U.S. Pat. No. 4,704,191 of Wedel, issued Nov. 3, 1987. In the devices suggested in this reference, an electromagnet is the motive device, and magnetic attraction between the electromagnet and the backing roll provided a squeezing or pressing force to the felt and web. Since this type of apparatus requires a direct physical contact with the belt, such as through a stainless shoe, friction is formed at the nip by the pressing force. This friction is a source of unnecessary wear, heat and wasted energy. The arrangements suggested by this reference therefore require the application of a liquid, such as water, as a lubricant and coolant to reduce friction and to remove heat.